You’re ready for bed, so you turn off the lights and pull down the shades. Sure, a little light may stream from the sides of the window, or beam from your alarm clock, or TV modem, or cell phone.
No big deal, you say?
Think again. It turns out that even tiny amounts of nighttime light—from any source—may be harmful to your heart.
One recent study found that older adults ages 63 to 84 who were exposed to even moderate amounts of ambient light during bedtime were more likely to be obese, have diabetes, and have high blood pressure – all risk factors for heart disease – compared to adults who were not exposed to any light during the night. The study, supported by the NHLBI, appeared in the journal SLEEP.
Another study involving adults in their 20s showed that light exposure during sleep can increase insulin resistance, a risk factor for diabetes, the following morning. That study, also funded by the NHLBI, was published in PNAS.
“The link between light at night and cardiovascular disease has been overlooked for a long time. Now, people are beginning to recognize that this is a problem,” said the SLEEP study’s corresponding author Minjee Kim, M.D., an assistant professor of neurology at Northwestern University Feinberg School of Medicine’s Center for Circadian & Sleep Medicine in Chicago.
